[beachnet] New article

Journal of Applied Microbiology
Volume 107 Issue 5, Pages 1518 - 1527

ORIGINAL ARTICLE
Application of microbial source tracking methods in a Gulf of Mexico field 
setting
A. Korajkic, B.D. Badgley, M.J. Brownell and V.J. Harwood 
Department of Biology, University of South Florida, Tampa, FL, USA
Correspondence to Valerie J. Harwood, Department of Biology, University of 
South Florida, 4202 East Fowler Avenue, SCA 110, Tampa, FL 33620, USA. 
E-mail: vharwood at cas.usf.edu
Copyright Journal compilation © 2009 The Society for Applied Microbiology

KEYWORDS
enterococci ? environmental water ? faecal ? faecal coliform ? markers ? 
microbial source tracking ? water quality

ABSTRACT
Aims: Microbial water quality and possible human sources of faecal 
pollution were assessed in a Florida estuary that serves shellfishing and 
recreational activities.
Methods and Results: Indicator organisms (IO), including faecal coliforms, 
Escherichia coli and enterococci, were quantified from marine and river 
waters, sediments and oysters. Florida recreational water standards were 
infrequently exceeded (6?10% of samples); however, shellfishing standards 
were more frequently exceeded (28%). IO concentrations in oysters and 
overlaying waters were significantly correlated, but oyster and sediment 
IO concentrations were uncorrelated. The human-associated esp gene of 
Enterococcus faecium was detected in marine and fresh waters at sites with 
suspected human sewage contamination. Lagrangian drifters, used to 
determine the pathways of bacterial transport and deposition, suggested 
that sediment deposition from the Ochlockonee River contributes to 
frequent detection of esp at a Gulf of Mexico beach.
Conclusions: These data indicate that human faecal pollution affects water 
quality in Wakulla County and that local topography and hydrology play a 
role in bacterial transport and deposition.
Significance and Impact of the Study: A combination of IO enumeration, 
microbial source tracking methods and regional hydrological study can 
reliably inform regulatory agencies of IO sources, improving risk 
assessment and pollution mitigation in impaired waters.



Murulee Byappanahalli, Ph. D.
Research Microbiologist
U.S. Geological Survey, Great Lakes Science Center
Lake Michigan Ecological Research Station,
1100 N. Mineral Springs Road
Porter, Indiana 46304
Phone: (219) 926-8336 ext. 421
Fax:      (219) 929-5792
E-mail: byappan at usgs.gov
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